DeLancey, Scott. Lhasa Tibetan. 2003. hh:s:DeLancey:Lhasa
High and low tone are only contrastive on word-initial syllables and spread rightward. Falling tone is only contrastive word-finally and is otherwise usually realized as a long vowel, although in some words it can be realized as short: _bod_ /pʰø˦˨ˀ/ "Tibet" ~ _bod-pa_ /pʰøpa/ "Tibetan person". (So short fronted vowels are included here as marginally contrastive.)